Too little is known generally about the cost of the various operations carried out in libraries. At present, new techniques are being devised using computers to store, sort, file and reproduce data formerly dealt with by traditional manual methods. Computer time, however, is expensive, and the computer programs to handle bibliographic data are difficult and costly to write and test. There is a danger that the new techniques may simply be too expensive. This study reports on three cataloging systems, and the costs incurred by each, employed at the University of Southampton Library: manual, mechanized (using a tape typewriter), and automated (using MARC data). (Author/SJ)